Revert "julia: fix i686 build"

This reverts commit 02fc4551f5d1eeb657cddea4658eb4212518311c.

pkgs/development/compilers/julia/0.3.nix

···
   nativeBuildInputs = [ gfortran git m4 patchelf perl which python2 ];
 
   makeFlags =
-    [
+    let
+      arch = head (splitString "-" stdenv.system);
+      march =
+        { "x86_64-linux" = "x86-64";
+          "x86_64-darwin" = "x86-64";
+          "i686-linux" = "i686";
+        }."${stdenv.system}" or (throw "unsupported system: ${stdenv.system}");
+    in [
+      "ARCH=${arch}"
+      "MARCH=${march}"
+      "JULIA_CPU_TARGET=${march}"
       "PREFIX=$(out)"
       "prefix=$(out)"
       "SHELL=${stdenv.shell}"